Certain pyridylmethylsulfinyl-carbamates

ABSTRACT

HERBICIDAL ACTIVE SULFOXIDE COMPOUNDS ARE DESCRIBED HEREIN. THE COMPOUNDS HAVING THE FOLLOWING GENERAL FORMULA:   R-SO-CO-N(-R1)-R2   WHEREIN R IS SELECTED FROM PYRIDYLALKYL, R1 AND R2 TAKEN TOGETHER FORM A HETEROCYCLIC RING STRUCTURE HAVING FROM 2 TO 10 CARBON ATOMS.

United States Patent Office 3,816,436 Patented June 11, 197 4 ABSTRACT OF THE DISCLOSURE Herbicidal active sulfoxide compounds are described herein. The compounds have the following general formula:

i 1 RSCN\ R: wherein R is selected from pyridylalkyl, R and R taken together form a heterocyclic ring structure having from 2 to 10 carbon atoms. 7

DESCRIPTION OF THE INVENTION This invention is directed to a novel group of compounds which may be generally described as sulfoxide derivatives of thiocarbamates which are highly active herbicides. The compounds of the present invention are represented by the generic'formula:

n i R-S-C-N R: wherein R can be selected from pyridylalkyl, R and R taken together form a heterocyclic ring structure having from 2 to 10 carbon atoms.

The above-noted compounds can be prepared by reacting an oxidizing agent such as peracetic acid or m-chloroperoxybenzoic acid with a thiocarbamate compound corresponding to the following formula:

wherein R, R and R have been defined above. The reaction is carried out in the presence of a solvent such as chloroform, methylene chloride, benzene or toluene, and at a reduced temperature of from about -25 C. to about 15 C. The amount of oxidizing agent used must be at least one molar equivalent to form the sulfoxide derivative.

The thiocarbamate compounds are known herbicides and their method of synthesis is known; see US. Pats. 2,913,327, 2,983,747, 3,133,947, 3,175,897 and 3,185,720 for example. However, the use of these thiocarbamates as reactive intermediates to form other compounds that also have pesticidal activity is unexpected.

In order to illustrate the merits of the present invention the following examples are provided:

EXAMPLE 1 O CHz-CHz-CH: CHr- JN CHrCHg-C H A solution was formed containing 11.0 grams (0.044 mole) S-(3-pyridylmethyl)-1-hexahydro 1H azepine-lcarbothioate dissolved in 200 cc. of methylene chloride. This solution was cooled to 15 C. in a Dry Ice bath.

Then, 9.0 grams (0.044 mole) of m-chloroperoxybenzoic acid was added portionwise over a period of 1.5 minutes. The mixture was stirred for 1 hour and the temperature was raised to 5 C. and held for 0.5 hours. Then, the mixture waswarmed to room temperature. The reaction mixture was transferred to a separatory funnel and treated 4 times with 50 milliliters of a 5% sodium car bonate solutiodfollowed by two 50 milliliter water washes. After drying over MgSO the solvent was removed by vacuum to yield 8.3 grams of product, n --1.5762.

Other compounds were prepared in an analogous manner starting with the appropriate starting materials as outlined above. The following is a table of compounds representative of those embodied by the present invention. Compound numbers have been assigned to them and are used for identification throughout the balance of the specification.

TABLE I n R-S (Oh-C-N Compound number R R1 R2 1 CH --CHr-CHa-CH: I -oH,-oi1,-oi1, N

2 Same as above;

Herbicidal screening tests As previously mentioned, the novel compounds herein described are phytotoxic compounds which are useful and valuable in controlling various plant species. Compounds of this invention are tested as herbicides in the following manner.

Preemergence herbicide screening test.--Using an analytical balance, 20 mg. of the compound to be tested is weighed out on a piece of glassine weighing paper. The paper and compound are placed in a 30 ml. widemouth bottle and 3 ml. of acetone containing 1% Tween 20 is added to dissolve the compound. If the material is not soluble in acetone, another solvent such as water, alcohol or dimethylformamide (DMF) is used instead. When DMF is used, only 0.5 ml. or less is used to dissolve the compound and then another solvent is used to make the volume up to 3 ml. The 3 ml. of solution is sprayed uniformly on the soil contained in a small Styrofoam flat one day after planting weed seeds in the flat of soil. A No. 152 DeVilbiss atomizer is used to apply the spray using compressed air at a pressure of 5 lb./sq. inch. The rate of application is 8 1b./acre and the spray volume is 143 gaL/acre. I

,On the day preceding treatment, the Styrofoam flat, which is 7 inches long, 5 inches wide and 2.75 inches deep, is filled to a depth of 2 inches with loamy sand soil. Seeds of seven different weed species are planted in individual rows using one species per row across the width of the flat. The seeds are covered with soil so that they are planted at a depth of 0.5 inch. The seeds used are hairy crabgrass (Digitaria sanguinalis), yellow foxtail (Serterz'a glauca), watergrass (Echinochloa crusgalli), red oat (Avena sativa), redroot pigweed (Am'aramhus retroflexus), Indian mustard (Brassica juncea) and curly dock (Rumex crispus). Ample seeds are planted to give about 20 to 50 seedlings per row after emergence depending on the size of the plants.

After treatmentfthe flats are" placed in the greenhouse at -atemperature'=of-=-79' te- '85 Frand 'wateredby' sprinkling. 'Ilwo weeks after treatment the degree of injury or control is determined by"'comparison with untreated check "plants-of the same age. The injury rating from '0 to 100% is 'recorded'for each species'as percent control with representing no injury and 100% representing complete kill.

Post-emergence herbicide screening test-Seeds plant species, including hairy crabgrass, watergrass, red oat, mustard,"cnrly dock and pinto-"beans (Phaseolus vulgaris) are planted in the Styrofoam flats as described above for pre-emergence screening. The hats are placed in the greenhouse at 70 to 85 F. and watered daily with a sprinkler. About 10 to 14 days after planting when the primary leaves of the bean plants are almost fully expanded and the first trifoliate leaves are just starting to form, the plants are sprayed. The spray is prepared by weighing out 20 mg. of the test compound, dissolving it in ml. of acetone containing 1% Tween and then adding 5 ml. of water. The solution is sprayed on the foliage using a No. 152 DeVilbiss atomizer at an air pressure of 5 1b./sq. inch. The spray concentration is 0.2% and the rate is 8 lb./acre. The spray volume is 476 gal./acre.

[Injury ratings are recorded 14 days after treatment. The rating system is the same as described above for the preemergence test.

The results of these tests are shown in Table II.

TABLE II.EE RBICIDAL ACTIVITY-SCREENING RESULTS Percent control at 8 lb./a.

Average for seven plant species in the preernergence test and for six plant species in the postemergence test.

of six The compounds of the present invention can be used irranyronvenient form. This, the compounds can be made into emulsifiable liquids, emulsifiable concentrates, liquid, wettable powder, powders, granular or any other convenient form, and applied to the soil to control the undesired vegetation.

What is claimed is: I 1. A compound represented by the following generic formu1a:. H f r t ,nppw

IR-S- -CN 1' wherein R is selected from pyridylmethyl, R and R 15 taken together form -CHz-CH -CHz -C zzr 2. The compound as set forth in claim 1 wherein R is 4 -CH I \N 7' v 3. The compound as set forth 'in claim 1 wherein R is References Cited UNITED STATES" PATENTS 3,579,525 5/1971 Tilles et al 2-60--294.8 E 3,634,436 1/ 1972 Domenico 260-294.8 F

ALAN L. ROTMAN," Primary Examiner us. c1. X.R. 71-94; 260--293.69;-294.8 o 

